How would you balance: #(NH_4)_2SO_4 + KOH -> K_2SO_4 + NH_3 + H_2O#?
You balance it stoichiometrically. What do I mean?
In every chemical reaction, both MASS and CHARGE are conserved. This is stoichiometry: for every product particle, there is a corresponding reactant particle.
Does this reaction satisfy the condition of stoichiometry? Charge is balanced certainly, but what about mass? There are 10
Stoichiometry is not only practised by chemists. It is practised by shop-keepers, bankers, and salesman. For every credit there must be a corresponding debit. If there is not then someone, (YOU!), has made a mistake.